Group III nitride semiconductors, which are compound semiconductors, have a wide band gap, and therefore, they are widely used as materials for light-emitting devices, such as blue, green, and other color LEDs (light-emitting diodes), LDs (laser diodes), and the like. Such devices are configured by laminating a p-type semiconductor layer (p-type layer) and an n-type semiconductor layer (n-type layer) by the epitaxial growth process.
In order to manufacture such a structure with a good quality being provided at a low cost, a p-type layer and an n-type layer are epitaxially grown on a growth substrate made of a material other than the group III nitride semiconductor in general. In this case, the type of material which can be used as a growth substrate for obtaining a semiconductor layer with a particularly good quality is limited. For example, gallium nitride (GaN), a typical group III nitride semiconductor, can be grown on a growth substrate formed of SiC, sapphire, or the like, by the MOCVD (metal organic chemical vapor deposition) process, the HVPE (hydride vapor phase epitaxy) process, or the like.
However, since sapphire is an insulator, it is required to provide two electric contact portions on the top face of a semiconductor layer laminated thereon, which has caused problems that the effective light-emitting area is narrowed down for a given substrate area, as compared to the conductor substrate, and both electrodes being provided on the same face locally increases the current density, resulting in the device being deteriorated due to the heat generated.
Then, a method for manufacturing a light-emitting device utilizing the lift-off technology is disclosed (for example, Patent Document 1 to be referenced). With this manufacturing method, an n-type layer, a p-type layer, and a p-side electrode are sequentially formed on a sapphire substrate, which is followed by newly bonding a conductive substrate on the side of the p-side electrode as a supporting substrate.